Spun polyester strands and method for making

ABSTRACT

Novel spun polyethylene terephthalate strands of improved percent elongation at break and initial modulus are obtained by (1) passing the strand under tension through a jet gas stream such as steam at a rate and gas temperature that effects fusion to the degree that the pulse propagation of the treated strand over a strand distance of 60 centimeters while under 20 grams tension is reduced to less than 300 microseconds or (2) passing the spun strand under tension around a roll heated to a temperature of about 175* to 195* C. at a rate of about 300 to 500 feet per minute.

United States Patent Ammons et a1.

[54] SPUN POLYESTER STRANDS AND METHOD FOR MAKING [72] Inventors: Robert L. Ammons; Robert B. Moore, Jr., both of Kingsport, Tenn.

Eastman Kodak Company, Rochester, N.Y.

[22] Filed: July 31,1969

[21] Appl.No.: 846,419

[73] Assignee:

[451 May 23, 1972 Primary Exarrdner-Donald E. Watkins Attorney-Cecil D. Quillen, Jr. and William P. Heath, Jr.

[ ABSIRACT Novel spun polyethylene terephthalate strands of improved percent elongation at break and initial modulus are obtained by l passing the strand under tension through a jet gas stream such as steam at a rate and gas temperature that efi'ects fusion to the degree that the pulse propagation of the treated strand over a strand distance of 60 centimeters while under 20 grams tension is reduced to less than 300 microseconds or (2) passing the spun strand under tension around a roll heated to a temperature of about 175 to 195 C. at a rate of about 300 to 500 feet per minute.

10 Claims, 2 Drawing Figures PATENTEDMAYZB 1912 I 3,664,114

ROBE L. AMMONS ROBERT BR ORE,JR

F G. 2 ENTORS BY My.

ATTORNEYS SPUN POLYESTER STRANDS AND METHOD FOR MAKING This invention relates to spun polyester and/or polyester blended strands such as threads or yarns having unique physical properties. More particularly, the present invention is directed to spun polyfilamentous strands of polyethylene terephthalate having improved elongation at break and initial modulus as well as other desirable properties.

l-ligh modulus and low breaking elongation are physical properties of prime importance in sewing thread and yarn manufacture. Ever since the introduction of spun synthetic fibers to the thread and textile industries, there have been persistent demands for spun threads and yarns of lower break elongation and higher modulus, particularly since spun synthetic polyester fibers do not as yet begin to approach the low percent elongation at break of cotton. Unfortunately, attempts to further improve these physical properties in spun fibers of the polyester, polyethylene terephthalate, have not been successful. Moreover, it has not been uncommon to find the attempts to improve the elongation and modulus properties adversely affecting other desirable properties in sewing threads or textile yarns as, for example, strength, resistance to scam puckering, thermal stability, sufficient flexibility to retain usefulness in sewing, weaving and/or knitting.

One object of the invention, therefore, is to provide a spun polyethylene terephthalate strand characterized by a modulus and breaking elongation heretofore unobtainable.

Another object of the invention is to provide a spun polyethylene terephthalate strand and spun blends of polyethylene terephthalate and other textile fibers which possess improved modulus and break elongation properties yet exhibits excellent strength, thermal stability, improved luster and whiteness, improved rigidity or stiffness while retaining sufficient flexibility to be useful in sewing, weaving and/or knitting.

Yet, another object is to provide a method which imparts to spun polyethylene terephthalate strands the aforementioned properties.

A further object of the invention is to provide a method which produces a spun polyethylene terephthalate strand exhibiting in addition to the aforementioned physical properties, a clean or smooth surface profile, a crepe hand and resembling a membrane that penetrates around and through the polyfilamentous strand so that the strand behaves like a single unity.

These and other objects of the invention are obtained by treating a spun strand consisting essentially of oriented fibers of polyethylene terephthalate or a blend of such polyethylene terephthalate fibers and other dissimilar textile fibers by one of two ways. According to one treating process, the preformed spun strand of polyester or polyester blend is passed under tension of between 0.08 gram per denier and 044 gram per denier, and preferably about 0.2 gram per denier, through a jet of heated inert gas such as nitrogen, steam, air and like gases at a rate and gas temperature that effects fusion, the degree of said fusion being sufficient to decrease the electrical pulse propagation of said strand, as measured over a strand distance of 60 centimeters while under 20 grams tension, to below 300 microseconds. In general, a passage rate of about 100 to 700 feet per minute and a jet gas temperature of about 240 to 260 C. are found suitable. The preferred heated gas is steam. For convenience, this process will hereinafter be referred to as the jet process.

The other treating process capable of providing the improved polyester strands comprises passing the spun strand of polyester or polyester blend under tension of between 0.08 gram per denier and 0.44 gram per denier, and preferably about 0.2 gram per denier, and at a rate of about 300 to 500 feet per minute around a roll heated to a temperature of about 175 to 195 C. Again for convenience, this process will hereinafter be referred to as the hot roll process.

Treatment of a spun strand of oriented fibers of polyethylene terephthalate in accordance with the abovedescribed processes provides a strand having a percent elongation at break of about 15 percent or less, preferably less than about 12 percent, an initial modulus of at least about 45 grams per denier per 100 percent elongation and a tenacity of about 4 grams per denier.

On the other hand, when the spun strand treated by either of the above-described processes is a blend of at least 50 percent by weight, usually about 50 to percent by weight, of oriented polyethylene terephthalate fibers and other dissimilar textile fibers, the resulting strand has a percent elongation at break of about 26 percent or less, an initial modulus of at least about 50 grams per denier per percent elongation and a tenacity of about 1.4 grams per denier. Exemplary of fibers which may be blended with the oriented polyethylene terephthalate fibers are cotton, rayon and other synthetic fibers (including fibers of other polyesters) commonly blended with polyester fibers in yarn and thread manufacture.

By the terms spun strand" as used in the specification and claims is meant a bundle of spun staple fibers and includes thread, yarn and the like.

Spun polyethylene terephthalate strands treated in accordance with the invention are characterized by a percent elongation at break of about 15 percent or less, an initial modulus of at least 45 grams per denier per 100 percent elongation and a tenacity of about 3.9 to 4.3 grams per denier. The characteristics of blends of polyethylene terephthalate and other fibers treated in accordance with the processes of the invention will vary depending upon the particular fiber and the amount blended with the polyethylene terephthalate fibers but in general are as follows: A percent elongation at break of 26 percent or less, an initial modulus of at least about 50, and a tenacity of about 1.3 to 2.1 grams per denier.

The spun strands of polyester or polyester blends treated to obtain the novel strands of the invention may be obtained by well known melt-spinning processes for the preparation of threads and yarns, including stretching, heat-setting, and the like, the details of which are evident to those skilled in the art. Also, if desired, the polyester or polyester blend may be stabilized by known prior art processes for obtaining stability against hot air shrinkage, before treatment, in accordance with the present invention.

The accompanying drawings schematically represent the processes of the invention for the treatment of the polyester strands:

FIG. 1 represents the jet process, and

FIG. 2 represents the hot roll process.

Referring to FIG. 1, the polyester strand is passed from a supply 1 through a tensioning device 3, around two unheated rolls 5 and 7, through a steam jet 9 and then to winder take-up 1 l. The jet employed is of a design what would be capable of handling continuous filament yarns as large as 3,000 denier; however, as pointed out by the definition above, the invention is directed to spun strands and is not directed to continuous filaments. The steam introduced into the jet is heated to a temperature of 240 to 260 C. and the strand is passed through the jet 9 at a speed of 100 to 700 feet per minute.

Referring to FIG. 2, the polyester strand is passed from a supply 13 through tensioning device 15, around a roll 17 heated to a temperature of about to C., and cold (unheated) roll 19 for several wraps and then to a winder takeup 21. The pre-formed polyester strand is run over heated roll 17 and cold roll 19 at a constant length at a speed of about 300 to 500 feet per minute.

The following examples are included to further illustrate the present invention.

EXAMPLE 1 A thread of polyethylene terephthalate (manufactured by Eastman Kodak Company and known commercially as KODEL 421 fiber) having the properties shown in Table l was processed according to the procedure illustrated in FIG. 1 under the conditions shown in Table l. The physical properties of the treated thread are summarized in Table l.

TABLE I.-PHYSICAL PROPERTIES OF JET AND THREADS Physical properties Hot air Conditions Strength Percent shrinkage Sample M elonga- Mod- 171 C.- No. Process F.p.m. C. Tension, gms. Denier G./d. Ounces tion ulus 18' Comments "2-1 Jet 700 260 35 (.l74g./d.) 201 4.30 31.0 11.9 62.9 7.6 v 724 m 300 260 35 .172 g./d.) 203 4.35 30.4 11.6 75.8 -s.s l u gi ggg and 724 ct 100 260 35 (.164 d. 213 3.96 29.8 11.1 79.5 -42 Que 804- 50/2 Kotlel 421 fiber control 226 4. 27 35. 4 16. 8 25. 4 6.1

The data of TABLE 1 establishes the unusually high initial modulus and low breaking elongation as well as improved strength (G/D) imparted to the thread. Furthermore, the examination of the processed threads showed them to have a smooth profile, a unique luster, stiffness with flexibility and a crepe"hand.

Study of the data of Table 1 indicates that as the process speed is decreased, the thread strength is slightly lowered, the

treated thread did not exhibit a crepe hand or a smooth profile. The same profile associated with the pre-formed spun thread is retained.

Close study of the data of Table 11 indicates that in the hot roll process of the invention, an increase in temperature at slow process speeds (300 F .P.M.) lowers the breaking elongation and increases the modulus without affecting the strength or the shrinkage properties. At faster process speeds (500 F.P.M.) an increase in temperature tends to increase modulus, breaking elongation and shrinkage potential. There is no apparent adverse effect on strength The data further shows that slowing the production rate while maintaining a roll temperature of 175 C. significantly improves strength, lowers the breaking elongation and increases modulus. At a roll temperature of 195 C., the same relationship seems to exist except that hot air shrinkage is adversely affected by a decrease in production rate.

TABLE II.-PHYSICAL PROPERTIES OF H.R. THREADS Physical properties Hot air Conditions Strength Percent shrinkage Sample elonga- Mod- 171 C.- No. lrovl-ss F.P.lll. (1. Tension, gins. Denier G./d. Ounces tion ulus 18 Comments I101. roll 500 175 20 (.092 g./(}.) 216 3g) 32.; 15.? 48. 8 5. 8 .4 1 16 2 .005 211 .5 33. 1. 6.1 .2 H3 z g 3 8 210 4 54 33 6 7 3 6 8 Similar eontlrol in appearance. except 19-4 do... 500 1115 20 .092 g./d.) 217 4.37 33. 4 14.9 63.1 -s. 0 umqu 19-5 do 500 225 20 (.095 g./(l.) 211 4. 33.1 16. 3 78. 2 -7. 8 804-1. /2 Kodel 421 fiber control 226 4. 27 35. 4 16. 8 25. 4 (i. 1

The data of Table 11 illustrates the improved low breaking EXAMPLE 111 elongation, high initial modulus and improved strength (G/D) provided the pre-formed thread by the hot roll process of the invention.

Also, examination of the treated thread showed the thread possessed as well a unique luster and stiffness with flexibility. Unlike the steam jet process of Example 1, however, the

The treating processes of Examples 1 and II were repeated 0 under the conditions shown in Tables ill and lll(a). In

addition, runs were also made with threads which were first stabilized by autoclaving before either the jet stream or hot roll treatments of the invention. The results of the runs are summarized in Tables in and III( a).

Process conditions Thread physical properties Shrinkage Feed Roll Strength Percent Sample rate, temp, breaking Hot air Water number f.p.m. C. Wind tension, gms. Denier G./d. Oz. elongation Modulus 171 C.18 100 C.2

REGULAR POLYESTER THREAD AUTOGLAVEl) POLYESTER THREAD .55 l 701) 270 (BN2 gJll.) ltlti 5.115 35. 5 15.0 25 2 7111) .1711 1K (.080 gL/(L) 3. 8-1 311. 2 1H. 5 L55 "1. 3111) 15111) IN (.UHU './I|.) 3.114 31.1] [5.7 25 H10 1151) 4(1 (.171! K./(l.) Ii. 71$ 311.11 11.4 NEH l. (uutmlnutm'lnvml111.275 l. -l III. l0. 1

TABLE III(a).-PHYSICAL PROPE RTIES-HEATED ROLL PROCESS Process conditions Thread physical properties Shrinkage Feed Roll Strength Percent Sam ple rate, temp, breaking Hot air. Water, number Mun. C. Wind tension, gms. Denier G./d. Oz. elongation Modulus 171 C.18 C.2 Regular polyester thread 50!) W5 40 (.204 u./ l.) 1116 4. )8 33. 8 14 5 66. 43 -6. 8 -2. 2 mm 17!: 411 (.206 g./1l.) 194 4. 9!! 33. 3 l5. (i6. 30 6. 4 -1. 8 300 I115 40 (.205 g./ l.) 195 4. 79 34. 8 14. 3 73. 26 6. 0 1. 8 500 1115 40 (.203 gJd.) 197 4. 95 33. 14. 5 65. 58 -6. 2 2. 0 Control 226 4. 27 34. 0 l6. 8 -6. 2 1. 2

Autoclaved polyester thread 500 175 (.179 g./d.) 223 4. 14 32. 5 18. 3 68.15 -3. 8 1. 8 300 175 40 (.179 g./d.)- 224 4. 17 32. 8 18. 9 50. 73 -3. 8 -1. 8 300 195 40 (.181 g./d.) 220 4. 28 33. 1 17. 2 56. 54 4. 2 1. 8 500 195 40 (.179 g./d.) 223 4. 28 33. 3 17. 7 61. 4. 4 2. 0 DA894P.. Control autoclaved at 275 F.1 hr. 228 3. 91 31. 5 19. 1 29. 8 --1.8 0.0

The data of Tables III and III(a) confirm the results of Examples l and II and shows further that the unusual properties are imparted to autoclave stabilized threads as well as to unstabilized threads by either the steam jet or hot roll process. The threads stabilized by autoclaving before treatment with either process, however, did not retain their stability properly after treatment.

EXAMPLE IV EXAMPLE V The unstabilized and stabilized threads treated as described in Example III were subjected to the pulse propagation test. This test is designed to time the passage of an electrical impulse over a given distance. The conditions of the test and the time required to send the electrical signal over the distance of a control thread are given in Table IV below. A detailed description of the pulse propagation test can be found in Table IV.

puckering before and after washing. The results were reported in Table V below.

TABLE V.SEAM PUCKERING RATINGS Seam puckering grade After one 140 Before washing F. wash Sample number Process Autoclaved A B Ave. A B Ave.

1 1 l 1 l l puckering; 2, moderate puckering;

Key: 0, no puckering; 1, slight 3, severe puckering (not acceptable).

The results show that satisfactory seams were sewn with all threads. In addition, visual inspection for seam puckering before and after washing indicated that the threads subjected to the jet stream process may offer improved resistance to puckering.

TABLE IV.PULSE PROPAGATION, MICROSECONDS Feed Jet Roll rate, temp, temp, Sample number i.p.m. C. C. Autoclaved Average readings (S) Test conditions 276 F.1 hr.-. 8...

894-P control).

l Kodel 421 filament. *Fs= full scale.

EXAMPLE VI The treated threads of Example III were subjected to a sewing test on a lock stitch machine at 10 S.P.I. in 20-inch increments. The fabric sewn with the threads was a 4 once durable press /35 Kodel 421 fiber/cotton sheeting. In addition, seams with each thread were made and graded for seam 261 60 cms. distant.

20 gms. tension.

*Fs-400 microsecs.

(control) EXAMPLE VII Three textile yarns identified in Table VI having the physical properties also shown in Table VI were subjected to the jet stream and hot roll processes described above employing the processing conditions specified in the Table. Table VI reports the results.

TABLE VI.TEXTILE YARNS Wind Percent Hot air Sample Temp, 0., tension, Strength, breaking Modulus, shrinkage. number and process gnlS. gJd elongation g./d. 175 C.-18 81-7 65/35 Kodel 421 fiber/cotton .1 260 C.jet 30 1. 78 14. *200. 00 1. 6 81-15 65/35 Kodel 421 fiber/cotton. 194 C.roll. 12 1. 99 26. 6 64 4. 6 65/35 Kodel 421 fiber/cotton-" Control 2. 07 28. 0 33. 85 7. 4 81-8 50/50 Kodel 421 fiber/cotton... 260 C.-jet 30 1. 45 8. 1 211.00 1. 6 81-16 50/50 Kodel 421 fiber/cotton 194 C.-roll 13 1. 37 7. 8 78. 34 3. 0 50/50 Kodel 421 fiber/cotton Control 1. 40 18. 0 34. 00 3. 8 These samples all run on Instron at 100% elongation: i.e., 10/min. chart speed; 10/min. crosshend speed; 10 sample; 1.000

gnL. full scale load.

Repeated at elongation scale: 10 The Modulus was calculated to be: 81-7, 74.54; 81-8, 84.64.

The data of Table VI establishes the unique improvement in breaking elongation and modulus (G/D) provided polyethylene terephthalate-containing textile yarns by the processes of the invention. The treated yarns were also found to possess good luster and stiffness with flexibility.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove.

It is claimed:

1. A spun polyester strand consisting essentially of oriented fibers of polyethylene terephthalate, said strand having a percent elongation at break of about 15 percent or less, an initial modulus of at least about 45 grams per denier per 100 percent elongation and a tenacity of at least about 4 grams per denier.

2. The spun polyester strand of claim 1 having a percent elongation at break of less than about 12 percent.

3. A spun strand comprising a blend of oriented fibers of polyethylene terephthalate and at least one dissimilar textile fiber, said polyethylene terephthalate fiber constituting at least about 50 percent by weight of said strand, said strand having a percent elongation at break of about 26 percent or less, an initial modulus of at least about 50 grams per denier per 100 percent elongation and a tenacity of at least about 1.4 grams per denier.

4. The strand of claim 3 wherein the textile fiber is cotton fiber.

/min. chart speed; 2/min. crosshead speed; 10

sample; 500 gm., full scale load.

5. The strand of claim 4 wherein the polyethylene terephthalate fiber constitutes about 50 to percent by weight of said strand.

6. Spun strands of polyethylene terephthalate treated by heating under tension of between 0.08 gram per denier and 0.44 gram per denier at a temperature that affects fusion of the strand, the degree of said fusion being sufficient to decrease the electrical pulse propagation of said strand, as measured over a strand distance of 60 centimeters while under 20 grams tension, to below 300 microseconds.

7. A process for improving the initial modulus and percent elongation at break of a spun strand comprising polyethylene terephthalate which comprises passing said spun strand under tension of between 0.08 denier and 0.44 gram per denier through a jet of inert gas heated to a temperature of about 240 to 260 C. and at a rate sufficient to decrease the pulse propagation of said strand as measured over a strand distance of 60 centimeters while under 20 grams tension.

8. The process of claim 7 wherein the gas is steam.

9. The process of claim 8 wherein the rate of passage is about to 700 feet per minute.

10. A process for improving the initial modulus and percent elongation at break of a spun strand comprising polyethylene terephthalate which comprises passing the spun strand under tension of between 0.08 gram per denier and 0.44 gram per denier at a rate of about 300 to 500 feet per minute around a roll heated to a temperature of about to C.

nun-11 Pgggo UNTTED STATES PATENT OFFICE v CERTIFICATE CF CORREC'HN 5,664,.11M Dated May 25, 1972 Patent No.

Inventor-(s) Robert L. Ammons and Robert B. Moore. Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 24, between "at least" and "45 grams" insert ---about---.

Column t, Table III, the "Modulus" of 'Sample number 25-1" ("89.29") should be ---89.82---.

Column 5, line 30, "sheated" should be "sheathed".

Column 6, Table 'lll(a) the "Water, lOOfC.-2 of "Sample number 25-8" ("2.0" should. be -2.0---

Signed and sealed this 3rd day of October 1972.

(SEAL) Attest:

EDWAR MJIETCHERJR. ROBERT GOTTSCHALK Attestlng Offlcer I Commissioner of Patents TEC10261 

2. The spun polyester strand of claim 1 having a percent elongation at break of less than about 12 percent.
 3. A spun strand comprising a blend of oriented fibers of polyethylene terephthalate and at least one dissimilar textile fiber, said polyethylene terephthalate fiber constituting at least about 50 percent by weight of said strand, said strand having a percent elongation at break of about 26 percent or less, an initial modulus of at least about 50 grams per denier per 100 percent elongation and a tenacity of at least about 1.4 grams per denier.
 4. The strand of claim 3 wherein the textile fiber is cotton fiber.
 5. The strand of claim 4 wherein the polyethylene terephthalate fiber constitutes about 50 to 80 percent by weight of said strand.
 6. Spun strands of polyethylene terephthalate treated by heating under tension of between 0.08 gram per denier and 0.44 gram per denier at a temperature that affects fusion of the strand, the degree of said fusion being sufficient to decrease the electrical pulse propagation of said strand, as measured over a strand distance of 60 centimeters while under 20 grams tension, to below 300 microseconds.
 7. A process for improving the initial modulus and percent elongation at break of a spun strand comprising polyethylene terephthalate which comprises passing said spun strand under tension of between 0.08 denier and 0.44 gram per denier through a jet of inert gas heated to a temperature of about 240* to 260* C. and at a rate sufficient to decrease the pulse propagation of said strand as measured over a strand distance of 60 centimeters while under 20 grams tension.
 8. The process of claim 7 wherein the gas is steam.
 9. The process of claim 8 wherein the rate of passage is about 100 to 700 feet per minute.
 10. A process for improving the initial modulus and percent elongation at break of a spun strand comprising polyethylene terephthalate which comprises passing the spun strand under tension of between 0.08 gram per denier and 0.44 gram per denier at a rate of about 300 to 500 feet per minute around a roll heated to a temperature of about 175* to 195* C. 